1. Field of the Invention
The present invention relates to a mask for forming patterns of a semiconductor device, and, more particularly, to a mask for forming patterns of a semiconductor device, which can transfer the shape of a mask pattern as it is onto a photoresist.
2. Description of the Related Art
A predetermined pattern of a semiconductor device, for example, a gate electrode, a bit line, a metal wire, or the like, is generally formed by a photolithography technique.
A photolithography technique generally includes a sequence or series of steps of coating photoresist on a semiconductor substrate having a predetermined layer formed thereon, transferring a pattern formed on the mask (to be referred to as a mask pattern hereinafter) onto the photoresist by exposing the photoresist to light using a mask, and performing a develop, thereby forming a photoresist pattern. Thereafter, a desired pattern can be obtained by etching the predetermined layer using the photoresist pattern.
To obtain a desired shaped pattern using the photolithography technique, it is primarily necessary to transfer the shape of a mask pattern as it is onto a photoresist.
When a photoresist pattern is implemented by exposing mask patterns crossing each other in different directions, for example, a vertical pattern and a horizontal pattern, which cross each other in a perpendicular direction, a shape of the photoresist pattern and a shape of the mask pattern are different at the edge where the horizontal pattern and the vertical pattern of the mask pattern are connected by the optical proximity effect. In detail, the mask pattern is angulated at the connecting portion of the horizontal pattern and the vertical pattern, while the photoresist pattern is rounded at the connecting portion of the horizontal pattern and the vertical pattern.
Accordingly, it is necessary to develop techniques of accurately transferring a mask pattern as it is onto a photoresist by suppressing the optical proximity effect.